1. Technical Field
This invention relates to a threaded element for forming a threaded profile in the wall of a bore formed in a material, such as plastic, or a part, such as a zinc or aluminum alloy diecasting part, and for insertion into the bore so as to reinforce the bore. Threaded elements of this nature are used in products such as bicycles and electrical home appliances, and in various other industrial fields.
2. Prior Art
Frequently a bolt which is inserted into a threaded bore in a plastic material, or a zinc or aluminum alloy diecasting part is inadequately tight in light of the deficiency in strength of the aforementioned type of material or part when compared with steel. This fact makes the threaded profile of the threaded bore more likely to become ineffective or damaged. In such cases, it is, therefore, advantageous to install a threaded element within the threaded bore. A typical one of such kind is disclosed in U.S. Pat. No. 3,200,691 to Neuschotz, which has the same shape at the ends, and thus is advantageously installable in bidirectional way. When installed in a bore of a somewhat greater inner diameter than specifications dictate, however, the force with which the threaded element is retained against removal from the bore, hereinafter referred to as a pull-out strength, falls remarkably. This constitutes a significant problem with the threaded element of U.S. Pat. No. 3,200,691.